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New advice on pros and cons of breast screening

Tuesday 17 September 2013

“Women will be told more about the risk of breast screening”, says the Mail Online, adding that “millions of women invited for breast cancer screening will be warned about problems with the tests for the first time”.

The news follows the publication of an updated NHS information leaflet on breast cancer screening.

The revised leaflet, produced by the NHS Cancer Screening Programmes contains more detailed information on both the benefits and risks of screening. This has been done so that women can make an informed choice about whether to attend their screening appointment.

Although breast screening is thought to save about 1,300 lives from breast cancer per year in the UK, the leaflet now includes detailed information about the risks of screening. It points out that for every woman who has her life saved from breast cancer, about three women are diagnosed with a cancer that would never have become life threatening – which leads to unnecessary treatments, which often have a number of side effects.   

How is breast cancer screening done?

All women aged 50 to 70 are invited for breast screening every three years. Screening is carried out by female staff, who take a type of X-ray test known as a mammogram to detect abnormalities in the breasts. The breasts are X-rayed one at a time by being placed on the X-ray machine and gently but firmly compressed with a clear plate. Two X-rays are taken of each breast at different angles.

Most women find the compression uncomfortable, and occasionally it may be painful. However, the compression is necessary to ensure the mammogram is clear. Any discomfort will be over quickly. The results of the mammogram will be sent to you and your GP.

Why has the NHS breast cancer screening leaflet been revised?

The development of new breast screening information followed a recommendation from Professor Sir Mike Richards, former National Clinical Director for Cancer, that materials should be updated. Recent research, such as a 2013 study published in the Journal of the Royal Society of Medicine, have highlighted the issue of overdiagnosis of breast cancer. Overdiagnosis is when people receive unnecessary cancer treatment for a cancer that would not otherwise have been diagnosed.

There was a consensus of opinion that the previous screening leaflet did not make clear the fact that overdiagnosis occurs as a result of screening.

What evidence is the leaflet based on?

The leaflet is based on the findings of the Independent Breast Screening Review, led by Professor Sir Michael Marmot.

The Independent Breast Screening Review, carried out during 2012, looked at the best available evidence and expert opinion, into both the benefits and harms of breast screening. Its main finding was “that the UK breast screening programmes confer significant benefit and should continue”.

What information does the updated breast cancer screening leaflet provide?

The leaflet covers what breast cancer is and its symptoms, what happens during breast screening, breast screening results, information about the benefits and harms of breast screening, and gives contact details if women have questions about breast screening.

A larger portion of the updated leaflet now explains the possible benefits and risks of breast screening.

Although screening saves lives from breast cancer, it also identifies some breast cancers that would never cause harm. These breast cancers which would not cause women harm are indistinguishable from harmful breast cancers. This leads to women having treatments such as surgery, hormone therapy, radiotherapy and chemotherapy which they would not have needed. All of these treatments can have, sometimes significant, side effects.

The leaflet explains that for every one woman who has her live saved by screening another three women will have a diagnosis of cancer that would never have become life-threatening.

In addition, breast screening can have other risks: it can cause unnecessary worry and anxiety if women have a ‘false positive’ screening result – where the screening result is positive but further investigation finds no cancer. There is also a very small risk of the screening failing to detect any cancer and exposure to X-ray radiation causing cancer.

What has been the expert reaction to the revised breast screening leaflet?

Professor Sir Michael Marmot, chair of the independent breast screening review panel, and Professor in Epidemiology at University College was “pleased” with the new leaflet.

Professor Julietta Patnick, director of the NHS Cancer Screening Programmes, said: “We believe that the leaflet now available to women provides a balanced assessment of the benefits and risks of breast screening and will support them as they decide whether to attend their screening appointment.”


It is important to stress that the NHS breast cancer screening programme has saved thousands of lives. But screening is no magic bullet. It saves lives but also leads people to undergo unnecessary testing and diagnosis.

If you have been asked to attend a screening programme we recommend you read the leaflet carefully before making your mind up about attending.